Head
An extension added to the top end of a casting when the mould is poured in a vertical position and it is desired to obtain a surface that is free from scum and dirt. The sullage is pushed beyond the limits of the casting, lodging in the "head," leaving the former clean.
Another form of riser is one into which the metal is forced by head pressure after the mould is full, and may, if placed on the top, answer as a dirt receiver, or serve as a means for feeding. See RISER.